Hello everyone. Pretty nice site you got going on here. I got a couple questions to pose at the folks here. Just moved some renters out of my house in OK and I got to do some work to it to make it livable. Had vinyl in the kitchen area that had lived 99% of its useful life. While removing it discovered it was adhered to 3/8" plywood with medium wt felt. Pulled it up. Found layer of OSB. OSB looked really iffy; pondered it, it needed to come up. Layer of OSB with hvy felt over 1x6 on diagonal. 1x6 looks low side of "OK". Couple of boards will need replacing. I am surprised I didn't have more issues with squeaks as many boards are quite loose. We are looking at putting 1/2" exterior plywood on top of 1x6 then CBU and tile with porcelain tile. Or should I consider pulling up 1x6 as well and installing 5/8" plywood and save my self some grief? Some additional background. We plan on retiring and living in the house. I want to get all the floor issues resolved while I still get a monthly income coming in and able to still physically be able to repair it. Really don't want a floor debacle seven or eight years down the road on retirement salary and 51 year old back to boot. The house was built in 1963 or 1969 can't remember which right now. Think i got the deflection handled as well with joists of 2x8 with 16" centers. Appreciate all that weigh in and give some things to consider as well. Thanks again and have a great new year.

There's a couple other factors to determine if your joist system is stiff enough for tiles. In addition to 2x8's at 16" o.c. we need to know the species, grade and unsupported span of those 2x8's. You'll probably meet minimums, but lets be safe.

You can keep the old 1x6 subfloor, just repair or replace as necessary. Removing it will create new issues and lots more work cuz you'll have to install blocking under where the new and old meet. You might also compromise the structure since the walls as built on those 1x6's.

After repairing the subfloor, install 1/2" or thicker underlayment grade plywood. Fasten only to the subfloor, not to the joists. NO GLUE.

Install concrete board or matting per instructions, then tiles using the correct thin set mortar. Thin set comes only in powder form in a bag and you'll need it for the tiles and the concrete board too. There's much more of course, but I hope you have a good idea how to proceed.

Thanks Mr. Jaz for taking time for a response. Still prepping the floor. Removing old tongue and grove from foyer and hallways that will be tiled as well. I have a utility add on by previous owners that I was going to tile as well but upon measuring those joists I discovered 22" centers so I need to research joist additions to make that work. I wasn't able to tell much about the main house joists except they were 2x8 w/16" centers. They have insulation held in place with what appears as chicken wire. Thinking Oklahoma trick maybe Got another question if you come back by. Here in Oklahoma we got scorpion issues. When i put my floor back together i was really considering placing roofing felt between 1x6 and plywood. Also considering a small bead of that foam insulation in the perimeter of the floor where i am leaving that gap for expansion of the plywood. Think either of these would bite me in the fanny later? I realize the little buggers will still occasionally get in but rather not have the equivalent of I-70 for the little richards running roughshod through the house. Thanks and have a great New Year.

the chicken wire is a great trick for critters and paper will not hurt anything although not the norm. the plywood subfloor should be screwed and some people glue it down also. It will expand and contract at the same rate as the original floor so filling the edges will not hurt. the room will need more joists.

2 X 8's are the bare minumum and would be fine for carpet or sheet flooring but not for tile with a span longer then about 8'. I'd pore three footings, three new piers and add a double up 2 X 8's to use as a beam between the span.
Tile can not have any flexing under the floor.
I never leave that old 1 X in place, the nails pop, it flexes, it raises the floor to much when you added the proper materails to redo it. I cut it out with a Toe Kick saw and use Advantec subflooring glued and screwed into place using ceramic coated deck screws, then a layer of 1/2 A/C Plywood making sure the seams do not line up with the sub floor below. We use a pneumatic staple gun to attach it ever 4" on the edges and 6 to 8" in the field. !/4' Tile board set in thin set.http://www.thefloorpro.com/articles/...derlayment.php